Synthetic chloride transporters with the binding mode observed in a ClC chloride channel

A series of synthetic molecules bearing the same hydrogen bonding mode observed in StClC were prepared and their transport ability of chloride ion across a lipid membrane was systematically optimized.close4

Determination of Two Differently Manufactured Silicon Dioxide Nanoparticles by Cloud Point Extraction Approach in Intestinal Cells, Intestinal Barriers and Tissues

Food additive amorphous silicon dioxide (SiO2) particles are manufactured by two different methods—precipitated and fumed procedures—which can induce different physicochemical properties and biological fates. In this study, precipitated and fumed SiO2 particles were characterized in terms of constituent particle size, hydrodynamic diameter, zeta potential, surface area, and solubility. Their fates in intestinal cells, intestinal barriers, and tissues after oral administration in rats were determined by optimizing Triton X-114-based cloud point extraction (CPE). The results demonstrate that the constituent particle sizes of precipitated and fumed SiO2 particles were similar, but their aggregate states differed from biofluid types, which also affect dissolution properties. Significantly higher cellular uptake, intestinal transport amount, and tissue accumulation of precipitated SiO2 than of fumed SiO2 was found. The intracellular fates of both types of particles in intestinal cells were primarily particle forms, but slowly decomposed into ions during intestinal transport and after distribution in the liver, and completely dissolved in the bloodstream and kidneys. These findings will provide crucial information for understanding and predicting the potential toxicity of food additive SiO2 after oral intake

Characterization and Determination of Nanoparticles in Commercial Processed Foods

A wide variety of foods manufactured by nanotechnology are commercially available on the market and labeled as nanoproducts. However, it is challenging to determine the presence of nanoparticles (NPs) in complex food matrices and processed foods. In this study, top-down-approach-produced (TD)-NP products and nanobubble waters (NBWs) were chosen as representative powdered and liquid nanoproducts, respectively. The characterization and determination of NPs in TD-NP products and NBWs were carried out by measuring constituent particle sizes, hydrodynamic diameters, zeta potentials, and surface chemistry. The results show that most NBWs had different characteristics compared with those of conventional sparkling waters, but nanobubbles were unstable during storage. On the other hand, powdered TD-NP products were found to be highly aggregated, and the constituent particle sizes less than 100 nm were remarkably observed after dispersion compared with counterpart conventional bulk-sized products by scanning electron microscopy at low acceleration voltage and cryogenic transmission electron microscopy. The differences in chemical composition and chemical state between TD-NPs and their counterpart conventional bulk products were also found by X-ray photoelectron spectroscopy. These findings will provide basic information about the presence of NPs in nano-labeled products and be useful to understand and predict the potential toxicity of NPs applied to the food industry

Matched and Mismatched Phenomena in the Helix Orientation Bias Induced by Chiral Appendages at Multiple Positions of Indolocarbazole-Pyridine Hybrid Foldamers

A series of indolocarbazole-pyridine (IP) hybrid foldamers containing chiral residues at multiple different positions were prepared to reveal the matched and mismatched phenomena of local stereocenters on the induction of helical bias. These foldamers adopted stable helical conformations, thus affording well-resolved separate sets of ¹H NMR signals for right- (<i>P</i>) and left-handed (<i>M</i>) helices in water saturated organic solvents such as toluene and dichloromethane. The ratios of <i>P</i>- and <i>M</i>-helices were determined by integrating the ¹H NMR signals, in combination with the molar circular dichroism (Δε) and optical rotation ([α]_D) values. The degree of helical bias was larger in the IP foldamer bearing chiral residues at the termini relative to those at the pyridine side chains, but the preferred helix orientation was opposite to each other. Foldamers <b>5</b>^{<b>(</b><i><b>SS</b></i><b>)t(</b><i><b>SSS</b></i><b>)py</b>} and <b>6</b>^{<b>(</b><i><b>RR</b></i><b>)t(</b><i><b>SSS</b></i><b>)py</b>} with chiral residues at five different positions demonstrated the matched and mismatched phenomena of local stereocenters in <b>6</b>^{<b>(</b><i><b>RR</b></i><b>)t(</b><i><b>SSS</b></i><b>)py</b>} and <b>5</b>^{<b>(</b><i><b>SS</b></i><b>)t(</b><i><b>SSS</b></i><b>)py</b>}, respectively

Comprehensive Design of DC Shipboard Power Systems for Pure Electric Propulsion Ship Based on Battery Energy Storage System

With the strengthening of international environmental regulations, many studies on the integrated electric propulsion systems applicable to eco-friendly ship are being conducted. However, few studies have been performed to establish a guide line for the overall pure electric propulsion ship design. Therefore, this paper introduces the comprehensive design of DC shipboard power system for pure electric propulsion ship based on battery energy storage system (BESS). To design and configure the pure electric propulsion ship, 2 MW propulsion car ferry was assumed and adopted to be the target vessel in this paper. In order to design the overall system, a series of design processes, such as the decision of the ship operation profile, BESS capacity selection, configuration of the power conversion systems for propulsion, battery charging/discharging procedures, classification of system operation modes, and analysis of the efficiency, were considered. The proposed efficient design and analysis of the pure electric propulsion ship was qualitatively and quantitatively validated by MATLAB Simulink tool. The methodology presented in this paper can help design real ships before the system commissioning

Enzyme-Responsive Procarriers Capable of Transporting Chloride Ions across Lipid and Cellular Membranes

Adopting the concept of procarrier for the first time, we demonstrated the controlled transport of chloride ions across lipid and cellular membranes. Procarriers containing highly hydrophilic appendages were initially inactive due to the lack of their partitioning into lipophilic membranes but were activated to transport chloride ions in the presence of specific enzymes that were able to hydrolyze off the appendages to generate an active carrier under specific conditions. Namely, the procarrier with an ester-bond-linked appendage was most activated by an esterase (PLE) at pH = 7.4, whereas the procarrier with a glycosyl-bond-linked appendage was activated only by a glycosylase (AOG) under slightly acidic conditions (pH = 5.5–6). In addition to controlling chloride transport, hydrophilic appendages greatly increase the water solubility of the procarrier, which may improve the deliverability of a hydrophobic active carrier into a plasma membrane

Synthetic K⁺/Cl^–‑Selective Symporter across a Phospholipid Membrane

Synthetic molecules which selectively transport sodium or potassium chloride across a lipid membrane have been prepared. The salt carriers consist of two heteroditopic binding sites, an anion-binding cavity with three hydrogen bond donors and an azacrown ether for binding an alkali metal cation. The association constants between the carriers and chloride ion have been enhanced by 1 order of the magnitude in the presence of sodium or potassium ion in 10% (v/v) CD₃OH/CD₃CN, due to the formation of a contact ion-pair between the bound cation and chloride as demonstrated by the single-crystal X-ray structure of a sodium chloride complex. A series of transport experiments have demonstrated that the synthetic molecule functions as a mobile carrier of transporting salts via M⁺/Cl^– symport. Among alkali metal chlorides, the carrier with an 18-azacrown-6 exhibits a strong selectivity toward potassium chloride, while the carrier with a 15-azacrown-5 displays a moderate selectivity for sodium chloride

Pathophysiological Roles of Mucosal-Associated Invariant T Cells in the Context of Gut Microbiota-Liver Axis

Mucosal-associated invariant T (MAIT) cells are a subset of T lymphocytes expressing a semi-invariant T-cell receptor (TCR) present as TCR Vα7.2-Jα33 in humans and TCR Vα19-Jα33 in mice. They are activated by ligands produced during microbial biosynthesis of riboflavin that is presented by major histocompatibility complex class I-related (MR1) molecules on antigen-presenting cells. MAIT cells also possess interleukin (IL)-12 and IL-18 receptors and can be activated by the respective cytokines released from microbially stimulated antigen-presenting cells. Therefore, MAIT cells can be involved in bacterial and viral defenses and are a significant part of the human immune system. They are particularly abundant in the liver, an organ serving as the second firewall of gut microbes next to the intestinal barrier. Therefore, the immune functions of MAIT cells are greatly impacted by changes in the gut-microbiota and play important roles in the gut-liver pathogenesis axis. In this review, we discuss the nature and mechanisms of MAIT cell activation and their dynamics during different types of liver pathogenesis conditions. We also share our perspectives on important aspects that should be explored further to reveal the exact roles that MAIT cells play in liver pathogenesis in the context of the gut microbiota

The Epidemiology and Economic Burden of Clostridium difficile Infection in Korea

The prevalence of Clostridium difficile infection and the associated burden have recently increased in many countries. While the main risk factors for C. difficile infection include old age and antibiotic use, the prevalence of this infection is increasing in low-risk groups. These trends highlight the need for research on C. difficile infection. This study pointed out the prevalence and economic burden of C. difficile infection and uses the representative national data which is primarily from the database of the Korean Health Insurance Review and Assessment Service, for 2008–2011. The annual economic cost was measured using a prevalence approach, which sums the costs incurred to treat C. difficile infection. C. difficile infection prevalence was estimated to have increased from 1.43 per 100,000 in 2008 to 5.06 per 100,000 in 2011. Moreover, mortality increased from 69 cases in 2008 to 172 in 2011. The economic cost increased concurrently, from $2.4 million in 2008 to$7.6 million, $10.5 million, and$15.8 million in 2009, 2010, and 2011, respectively. The increasing economic burden of C. difficile infection over the course of the study period emphasizes the need for intervention to minimize the burden of a preventable illness like C. difficile infection

Helical Aromatic Foldamers Functioning as a Fluorescence Turn-on Probe for Anions

Indolocarbazole-pyridine hybrid foldamers are strongly fluorescent in an extended random conformation, but the fluorescence is completely quenched upon folding to a helical conformation due to the compact stacking between aryl planes in the backbone. Anion binding disturbs the helical conformation, thus regenerating the fluorescence of the foldamers. This unique property has been utilized to develop a fluorescence turn-on probe for anions such as sulfate and fluoride